Strain insulator



Jan. 17, 1933. w, CRAMER 1,894,292

STRAIN INSULATOR Filed March 12, 1926 Patented Jam-17, 1933 UNITED STATES PATENT OFFICE WALTER CRAMER, F CHARLOTTENBURG, GERMANY, ASSIGNOR TO LOCKE INSULATOR CORPORATION, OF BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND STRAIN INSUDATOR Application filed March 12, 1926, Serial No. 94,232, and in Germany March 28, 1925.

The invention relates to insulators, particularly those of the strain type.

The primary object of the invention, generally stated, is to provide an insulator embodying means for insuring draining off of water falling thereonto during rain storms or condensing thereon in misty or foggy weather.

The object of the invention, more specifically stated, is to provide an insulator of the elongated or rod type equipped with peculiarly arranged ribs which provide a path for rain or other water falling thereonto, the construction being such that the water will be permitted to flow off readily and rapidly without leaving an accumulation of dirt or other foreign matter in its wake as has been known,

to occur in certain types of insulators.

A further object of the invention is the provision of an insulator formed with a rib 2 or ribs arranged to provide a path permitting the draining or flowing away of the major portion of any water which may fall upon the insulator or accumulate thereon from any cause, whatever water remains providing a leakage path which will reduce the electrostatic stresses under wet weather conditions and thereby materially improve the efficiency of the insulator.

A still more specific object of the invention is to provide an insulator of the elongated or rod type with one or more helical ribs which by permitting rain or other water to flow or drain away will operate to cause a centrifugal action which will result in a tendency of the water to fly outwardly, breaking the natural cohesive tendency and quickly removing the water from the body or central portion of the insulator so that the efliciency thereof will not be impaired to any material extent even during severe rain storms.

An additional object of the invention is the provision of an insulator of this type in which the upper surfaces of the helical rib or ribs are inclined downwardly and outwardly so that any water falling or accumulating upon the insulator will gravitationally move outwardly toward the periphery of the rib or ribs and either drip olf or be thrown off by centrifugal action in case the downflowing stream acquires suflicient velocity.

To the attainment of the above and other objects and advantages such as cheapness in manufacture together with general efficiency, the invention consists in the detailed construction and arrangement to be hereinafter more fullydescribed and claimed and illustrated in the accompanying drawing in which:

Figure 1 is a side elevation of an insulator constructed in accordance with the invention.

Figure 2 is a cross section therethrough on the line 2-2- of Figure 1.

FigureS is a fragmentary detail section.

teferring to the drawing in detail,=I have shown the insulator as comprising an elongated body 1 of suitable insulating material such, for instance, as porcelain, whichbody is preferably cylindrical in shape and either hollow or solid as disclosed. Any desired means, not shown, may be provided at the ends 2 of the body for securing suspension elements or other connections thereto; In the present instance the body is represented as being of uniform size throughout though this is not necessarily the case inasmuch as there could be a variation if desired without in any way departing from the spirit of the invention. a

Formed upon the body and extending throughout any desired portion. thereof I provide a rib or ribs 3, two being shown in the present instance, which ribs extend helic'ally so as to provide a continuous path for any water which may fall or accumulate upon the insulator. The upper surfaces of the rib or ribs are inclined downwardly and out 85 wardly as clearly indicated at 4 in Figure 3 so that water falling or accumulating on the insulator will pass gravitationally away from the center or body to the outer edge or edges of the rib or ribs so that the central portion or body will be free from a continuous film of water. In case of a heavy downpour of rain, it is clear that the water will pass downwardly along the insulator with considerable velocity and as it follows the convolutions of the rib or ribs it will be given a whirling movement, the centrifugal force developed operating to throw off the water, this force breaking the cohesive effect and preventing a cascading effect between the successive con- 1 volutions. However, only the major portion of the water will be discharged. There will be an appreciable amount of water within the channel defined by the helical rib and this remaining water will provide an adequate leakage path for current so that the electrostatic stresses under wet weather conditions, and the like, will be reduced, thereby considerably increasing the efliciency of the insulator while not reducing, to any great extent, the arc-over value. Experience has demonstrated that this continuous path for current afforded by the flowing stream of water is of great benefit as it takes care of a condition which would otherwise result in disadvantage.

An insulator constructed in accordance with the invention will be found advantageous not only for the reason that an easy path has been provided for the draining away of any water but for the additional reason that the construction and shape of the parts are such that any dirt previously accumulated on the insulator will be washed away without leaving any ridges or deposits at any points in the area. The exact manner of use is of course a matter which will be readily apparent to those skilled in the art and, as a matter of fact, there is no particular limitation desired in this respect.

While I have shown and described a preferred embodiment of the invention, it should be understood that the disclosure is merely illustrative as the right is reserved to vary the shape, size and other details and to provide more or less ribs or convolutions thereof as may be preferred, these and other changes being possible Without departing from the spirit of the invention as defined by the claim hereunto appended.

Having thus described the invention, I claim: I

An insulator comprising an elongated body of dielectric material of cylindrical form with outwardly flaring end portions, the intermediate portion of the body having a helical rib thereon terminating short of said flaring ends and merging into the body adj acent said ends.

In testimony whereof I afiix my signature.

WVALTER CRAMER. 

